The ultimate fate of the Death Star may be completely wrong

If you're reading this, chances are you've watched (or plan to watch) Disney's "Rogue One: A Star Wars Story," the first of several standalone "Star Wars" movies that expands upon the main plot of the epic series.

Without spoiling anything beyond the trailers, "Rogue One" picks up at a critical moment: when the Empire has just finished building the Death Star and is flexing its planet-destroying muscles.

But there is something gravely wrong with the moon-size weapon's ultimate fate in the trilogy's final film, and physicists want you to know about it.

The Death Star II explodes into smithereens.Disney/Lucasfilm

The Death Star meets its final doom in "Return of the Jedi," the epic conclusion to the original "Star Wars" saga.

The colossal ship is orbiting the forested Sanctuary moon of the planet Endor and, after it's blown up, the Rebel Alliance and its hairy Ewok friends party in the trees. Everyone and everything is hunky-dory.

But ask a physicist — or a dozen, as Tech Insider did last year — what happens when you detonate a giant metal sphere above a lush green world. The answer is downright chilling.

"The Ewoks are dead. All of them," said one researcher and self-professed "Star Wars" fan, who wrote a white paper in 2015 that supported his conclusion.

Each scientist who responded to our emails quibbled over the exact details, yet a strong consensus emerged in support of a popular fan theory: The "Endor Holocaust" is inevitable, and a threat to the plausibility of any future movies (galactic bankruptcy be damned).

Responses after that, however, were grim.

Disney/Lucasfilm

Matija Cuk, who studies orbital dynamics, said the Death Star's reactor blows up the artificial satellite in about 1 second. This would eject huge chunks of debris at 220,000 mph, or six times faster than humanity's speediest spacecraft.

Planetary physicist Erik Asphaug, who studies giant impacts with moons and planets, refused to believe most of the Death Star would vaporize or turn into tiny bits upon exploding.

"Nuclear explosions in rock tend to vaporize the stuff nearby, melt the stuff a bit further away, and then break stuff farther away mechanically. The farther away, the less broken the bits become," Asphaug told Tech Insider.

Public domain

"So, I predict there will be huge chunks of the Death Star raining down on the Ewoks that might make their life unpleasant," he said — plenty big enough to reach the ground and make craters.

Yet Asphaug said the biggest problem for the Ewoks on a dense forest moon might be fire.

EPA/Noah Berger

"If thousands of wildfires go off at once, even if limited to one half of the planet, much of the surface will be a charred ruin," he said. "Their parties and celebrations will quickly change into emergency procedures to survive what could be a horrible nightmare."

Disney/Lucasfilm

The most detailed (and frightening) response came from planetary scientist Dave Minton, who sent Tech Insider, a former website of Business Insider, an exclusive four-page treatise in 2015. It begins: "The Ewoks are dead. All of them."

The white paper is based on a detailed, to-scale hologram projected in "Return of the Jedi."

Disney/Lucasfilm

From that image, Minton used physics equations to extrapolate diameters, masses, velocities, and orbital paths of Endor and the Death Star.

Disney/Lucasfilm

He also assumes that — since Ewoks, storm troopers, and rebels move like they do here on Earth — that the gravity of Endor is the same as our planet.

Reuters/Alexander Gerst/NASA

"I estimate that the bulk density of Endor is about 14,350 kg/m3," he told Tech Insider. "This is more than iron (8000 kg/m3) and less than uranium (19,100 kg/m3), so while the composition of Endor must be quite unusual, it is not impossible."

He also assumes, like Asphaug, that the Death Star is not vaporized and mostly shatters into a field of loose rubble.

"[M]ore or less what happens after the destruction is that the entire mass of the Death Star simply falls onto the location of the shield generator," he said.

Minton said the falling rubble field would look something like this animation of a colossal asteroid striking the Earth:

Striking Endor at more than 6,000 mph, Minton said "a Death Star-mass ball of fragments will leave behind a 700 km diameter crater. This is almost 4 times larger than the Chicxulub crater in Mexico that is associated with the dinosaur extinction."

NASA

"The aftermath of this impact would be to obliterate everything on the surface. No Ewok could withstand an impact of that magnitude."

"It is likely that the atmosphere would be so heated up ... that every body of water on the entire world would be flash heated to steam, and every forest would ignite into a global firestorm."